SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20ce945a259e010c76453262499b498fb0776f91b5cb019e9cd5ffdd49a4b0e4' 
  AND token = 'PeLxWgQQPuozcjfSyogOImKoU8UXnNce5x8yhQV9bm8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}